Increments of speed restriction
In the USA, speed restrictions may be set in 1 mph increments.
European practice varies: Restrictions might be issued in increments of 0.62 mph, 3.11 mph, or 6.21 mph. If the calculated limit is the same in two European countries, the posted speed restriction might vary nonetheless, due to different increments.
Adding this additional level of complexity won't improve understandability of this text (to put it mildly). Therefore, I will use 1 mph increments for all railroads, even though they might not follow US practice.
I expect, that European operation will adapt to US practice, as soon as more of the modern cab signaling is installed. With modern cab signaling, no reason for any other practice exists. Of course, this won't mean 1 mph, but 0.62 mph increments to be used.